There are known counting devices for counting particles suspended in a fluid, and these devices are used as detection systems in blood analyzers, as disclosed in U.S. Pat. No. 2,656,508, Japanese Examined Patent Application Publication No. S30-5699, U.S. Pat. No. 3,502,974, and Japanese Examined Patent Application Publication No. S42-2200. Such counting devices include bores, through which particles pass, and two electrodes. Passage of particles through the bores causes a change in electric current that flows through the electrodes.
Japanese Unexamined Patent Application Publication 2003-315296 discloses another known detection system in which the distance between two semiconductor (Si) substrates is determined according to the thickness of the insulator (SiO2). In such a detection system, the distance between two semiconductor substrates is determined with enhanced accuracy according to the thickness of the insulator, and therefore, the two semiconductor substrates can be positioned with enhanced accuracy so that the distance between the semiconductor substrates is made to be larger than but close in size to target substances. Accordingly, sensitivity is readily achieved.